big al,
the smear test is to test for blood in your stool. this is usually performed in a physical.

these little tests have saved lives.

I don't know how old you are but by a certain age everyone should have a colonoscopy performed to test for colon cancer or polyps.
they insert a scope and you can see the inside of your colon on a t.v. screen. it's really cool. they give you medicine thru I.V. so you aren't uncomfortable, or they put you to sleep totally. which only lasts about 10 minutes maybe less.
the colon is the large bowel. the colonoscopy can't reach the small bowels.
people who have a family history of colon cancer need to have this exam at an earlier age, depending on the doctor.

you can't feel polyps growing inside your colon. some of them can be very dangerous and can be malignant and others can be non malignant which is called "benign".

to answer your question when the medical society refers to black stools, I THINK the color is closely related to what wet coffee grinds resemble.

or I may be mixing that up with if someone vomits and blood is in it.
I may be mixing up the both. not sure. my memory is so bad at times.

I wouldn't worry unless you have a family history of colon cancer.

get your exams when you're supposed to and eat lots of healthy green vegetables and stay away from a lot of red meats and hopefully you won't have a problem up the road.

I wish you good health.

Linda